Silver halide emusions containing polyoxyalkylene sensitizers



United States Patent Johnson City, N.Y., assignors to General Aniline &Film Corporation, New York, N.Y., a corporation of Delaware No Drawing.Filed Sept. 19, 1962, Ser. No. 224,835

4 Claims. (Cl. 96-107) The present invention relates to photographicsilver halide emulsions and in particular to the sensitization thereofby the use of certain water-soluble polyoxyalkylene derivatives.

The use of polyoxyethylenes or derivatives of alkylene oxides withamines, phenols, alcohols and hexetolring dehydration products assensitizer for silver halide emulsions have been described in the priorart and in this connection reference is made to United States Patents2,423,549, 2,441,389, 2,240,472 and 2,400,532 and the like.

Generally the polyoxyethylene or the alkylene oxide derivatives have amolecular weight of at least 300, but preferably from 1500 to 10,000 ormore.

It has been recognized that these compounds are powerful sensitizers.Their use, however, has been limited because of their marked tendency toincrease the fog of photographic silver halide emulsions during storage,especially at elevated temperatures and humidities. To counteract thistendency and at the same time to take advantage of the sensitizingcharacteristics of the compounds, it has been necessary to use with thesensitizers special anti-foggants. This is attributable to the fact thatconventional anti-foggants such as referred to on pages 459 et seq. ofMees The Theory of the Photographic Process, published 'by the MacMillanCompany, New York, in 1946, are powerless to control the fog induced bythe sensitizer. Thus in U.S.P. 2,704,716 there is used as ananti-foggant hydromelonic acid or cyarneluric acid; in U.S.P. 2,716,062,4-hydroxy-6-alkyl-1,3,3a-7-tetrazaindenes and in USP. 2,728,666,specific compounds of mercury with amines or amine salts.

We have now discovered and rather surprisingly so that the alkyleneoxide derivatives obtained by the condensation of pentaerythritol with1,2-propylene oxide having molecular weight of at least 300 and whichare still water-soluble are completely efiective sensitizers for silverhalide emulsions without showing the excessive fogging tendency of thepreviously mentioned alkylene oxide compounds and that whatever foggingtakes place can be controlled by the employment of conventionalanti-foggants. Furthermore and rather unusually such condensationproducts not only have the function stated but in addition portray theproperties of reducing brittleness and static in film in which they arelocated.

Silver halide emulsions in intimate association or contact withcondensation products of pentaerythritol with 1,2-pyropylene oxidehaving a molecular weight of at least 300 or more constitute thepurposes and objects of the present invention.

The condensation product contemplated for use herein may be typified bythe following structural formula:

3,173,790 Patented Mar. 16, 1965 'ice in which the values of a, b, c,and d are such that the molecular weight of the compound is 300 andpreferably 10,000 or more.

U.S.P. 1,970,578 describes the formation of condensation products ofalkylene oxides on compounds containing a reactive hydrogen, such asalcohols, phenols, amines, acids and the like. The procedure envisionedby this patent may be used to produce the condensation products hereof.

It has been noted that the increase in sensitivity reduction ofbrittleness and static by the use of the pentaerythritol condensationproducts may be brought about through intimate contact or associationwith the silver halide emulsion. Thus it has been found that the desiredsensitivity may be achieved by adding the condensation product to thesilver halide emulsion, to an undercoating, an intermedicate coating, anovercoating, or a surface coating prior to the coating operation. Ifdesired, the condensation product may even be added during the actualpreparation of the emulsion either before or after washing the emulsion.

The condensation product described herein may be used in various typesof photographic emulsions, e.g., in non sensitized emulsions,orthochromatic, panchromatic and X-ray emulsions. If used withsensitizing dyes, it will be added before or after the dyes are added.The emulsions may be prepared with any of the usual silver halides suchas silver bromide, silver iodide, silver chloride or mixed silverhalide. The condensation products may be employed in emulsions intendedfor color photography, that is those containing color-forming compounds.The dispersing agents or colloid carrier for the light-sensitive halidesmay be any of the colloids used in photography such as gelatin,collodion, albumen, cellulose derivatives, PVA, or the like.

The following examples are illustrated for effectiveness of ourcondensation products of pentaerythritol with 1,2-pyropylene oxide as aspeed increasing element for photographic silver halide emulsions but itis to be understood that this invention is not restricted thereto.

Example I A silver halide emulsion in gelatin containing 4% silveriodide and 96% silver bromide was prepared in a conven tional manner andbrought up to its maximum lightsensitivity. It was then readied forcoating on film base, that is, melted at 40 C., and coating finals suchas sensitizing dyes, stabilizers and hardeners were added. A 10% aqueoussolution of a polyether produced by condensing 8 moles of 1,2-propyleneoxide with pentaerythritol was prepared and 10 cc. of this solution wasadded to a sample of the above described emulsion, containing about 0.4mol of silver halide. A sample of the same emulsion, but not containingthe speed increasing additive served as a control. The so preparedemulsion samples were coated on a cellulose ester base and dried.Samples of these film coatings were then exposed in a Type I BSensitometer and developed in a developer of the following composition:

Grams Metol 1.5 Sodium sulfite, anhydrous 45.0 Sodium bisulfite 1.0

Hydroquinone 3.0 Sodium carbonate, monohydrate 6.8 Potassium bromide z-.8

Water to make 1.0 liter.

Condensation Product'of 1,2- 6 Days Propylene Oxide and Relative After12' Oven Test Pentaerythritol Speed Dev. 7 and 4 Dev.

0 100 .13 .08 1 gram. 160 20 09 Quantity of Polyoxyethylene Laurylether'Added:

1 gram 150 28 16 Example 11 A silver halide emulsion in gelatincontaining 4% silver iodide and 96% silver bromide was coated on filmbase in a manner known'to the art. After the coating was performed, anaqueous gelatin solution containing 20 grams of gelatin per liter and1.2 grams of the condensation product of 1,2-propylene oxide andpentaerythritol was coated thereon'asan antiabrasion layer, saidcondensation product having a molecular weight of 450. After drying,film samples were exposed and processed as described in Example I. Thesamples described exhibited a relative speed of 175 with a fog of .20 ascompared With a type coating of the same emulsion having anantiabr-asion layer similar to that described above, but lacking thespeed increasing additive andhaving a speed of 100 and a fog of .13;

We claim:

1. In a photographic element a light-sensitive silver halide emulsionlayer having in intimate contact therewith a condensation product ofpentaerythritol with 1,2- ropylene oxide, such condensation producthaving a molecular Weight of at least 300.

2, In a photographic element a light-sensitive silver halide emulsionlayer which contains the condensation product of pentaerythritol and1,2-propylene oxide, such condensation product having molecular Weightof at least 300.

' 3. A photographic element comprising a support, a light-sensitivesilver halide emulsion layer containing a condensation product ofpentaerythritol With 1,2-propylene oxide, such condensation producthaving molecular Weight of from 300 to at least 10,000.

4. A photographic element comprising a support bear- 7 ing alight-sensitive silver brom-iodide emulsion containing about 1 gram per.4 mol of silver halide of the condensation product of 1 mol ofpentaerythritol With 8 moles of 1,2-propylene oxide.

References Cited in the file of this patent UNITED STATES PATENTS2,743,180 Carroll Apr. 24, 1956 2,927,918 Anderson Mar. 8, 19602,995,444 Dersch Aug. 8, 1961

1. IN A PHOTOGRAPHIC ELEMENT A LIGHT-SENSITIVE SILVER HALIDE EMULSIONLAYER HAVING IN INTIMATE CONTACT THEREWITH A CONDENSATION PRODUCT OFPENTAERYTHRITOL WITH 1,2PROPYLENE OXIDE, SUCH CONDENSATION PRODUCTHAVING A MOLECULAR WEIGHT OF AT LEAST 30.